Shunt for speaking-telephone systems



1(NoMode1.)

' P. W. JONES.

Shunt for Speaking Telephone Systems.

No. 238,399. Patented March 1,1881.-

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NPETERS. FNOTO-LITNOGRAPMEI. WASHINGTON. D. C.

rrnn STATES PATENT Fries.

FRANCIS W. .IONES, OF CHICAGO, ILLINOIS.

SHUNT FOR SPEAKING-TELEPHONE SYSTEMS.

SPECIFICATION formingpart of Letters Patent No. 238,399, dated March 1, 1881.

Application filed December 21, 1980. (No mo'lcl.)

T 0 all ti /L07 it may concern: I

Be it known that I, FRANCIS W. JoNEs, a citizen of the United States, residing at Chicago, in the county of Cook and State of lllinois,have invented certain new and useful improvements in Shunts for Speaking-Telephone Systems, of which the following is a specification.

My invention relates more particularly to that class of telephone-lines in which the alarm or signaling apparatus is operated by voltaic currents or by magneto-electric pulsations.

In operating this class of telephone-lines it is frequently desirable and necessary to place several different stations upon the same circuit, and also as a matter of economy and convenience to make use of the same conductor, both for signaling and for conversation, by means of suitable speaking-telephones of well known construction. A practical difiiculty has, however, been found to exist by reason of this organization of apparatus and circuits. The signaling apparatus at each station being actuated by an electro-magnet of the ordinary construction, it is obvious that this electromagnet must remain at all times in the main circuit, except when the telephone at the same station is in use, so that signals may be receieved on it at any moment; but it has been found by experience that telephonic vibrations or undulations are checked by being caused to pass through an electro-magnet, or, as it is sometimes expressed, an electro-magnet is more or less opaque to rhythmical vibrations. Consequently if a number of stations are placed upon the same line with their several signaling electro-magnets included in the main circuit. the telephonic vibrations which are transmitted to and fro between any two stations communicating with each other must necessarily pass through all the electromagnets in the circuit except their own, and by this means the vibrationsare weakened or absorbed to such an extent as to render conversation nearly or quite inaudible.

The object of my invention is to obviate this difficulty by-furnishing a path for the telephonic vibrations to pass the station without necessarily going through the coils of the electro-magnet, while at the same time the said elcct-ro magnet is so arranged as to respond readily to signaling-currents traversing the line.

In the accompanying drawings, Figure 1 is a diagram illustrating the application of my improvements to a signaling electro magnet actuated by voltaic or other electric currents of one polarity. Fig. 2 represents the application of the same to a signaling apparatus operated by alternating positive and negative pulsations, such as are produced by a magneto-electric generator.

Referring to the drawings, R represents an ordinary electro-magnet, which is supposed to be placed at a station upon the telephone-line. This electro-magnetis provided withthe usual soi'tiron armature and pivoted lever T, which latter may be utilized to actuate the signaling apparatus in any suitable and well-known manner. For example, it may be arranged as a relay to repeat the signals by means of a local battery upon a sounder, a hell, or other like instrument, or a bell-hammer may be attached directly to the lever T, as shown in Fig. 2. The armature-lever T may be provided with the ordinary retracting-spring, as shown in the figure. The armature-lever T vibrates between two contact-stops, 3 and 5. A shunt or branch circuit is connected with the main lineat the point 2, and is preferably connected first to the pivot of the armature-lever at the point 1, from whence a circuit is formed through said lever and its rear contactstop, 3, and thence, bya wire, to the pointon the main line beyond the eleetro-magnet R. The circuit from the point 2 to the p0int4tconstitutes a shunt-circuit passing around the electro-magnet B. In the position of the apparatus represented in Fi .1 the signalingcnrrent of the main line has been cut off at some other station. Consequently the electromagnet R has become demagnetized, and the armature-lever T being released is held against the contact-stop 3, thus closing the shunt-circuit around the electro-magnet. Unless the resistance of the helix of the electro-magnetR is very small it is necessary to insert an artificial resistance or rheostat, S, at some point in the shunt-circuit-as, for instance, between the points 1 and 2, as shown in the figure. In most cases the resistance of this shunt should be at'least equal to that of the helix of the electro-magnet R, although this proportion may be widely departed from without rendering the apparatus inoperative.

The rheostat S may be composed of any suitable material, such as a metallic wire, either straight or in the form of a helix; but I prefer to construct it of a coil or bobbin of wire of some metal which is a poor conductor ofelectricity-such, for instance, as German silver-and this wire is wound double or back on itself in the manner indicated in the figures, in order to neutralize the efi'ects of the induction of the electric current on itself, which takes place in the ordinary helix, and which tends to produce false vibrations and to confuse the tones as heard in the receiving-telephone.

When the parts are in the position shown in Fig. 1, it either avoltaic or a magneto-electric signaling-current of snf'ficient power be sent through the line, it will divide at the point 2, one portion going through the coils of the electro-magnet R to the point 4:, and the other portion going through the shunt to the same point, passing around or avoiding the electro-magnet. The electro-magnet being thus caused to attract its armature, the first movement of the latter interrupts the contact between the lever T and the stop 3, and thus breaks the shunt-circuit, after which the full power of the entire current passes through the coils of the electro-inagnet, and a signal is produced by the action of its armature T, in the manner hereinbefore described. It, however, a series of rhythmical or telephonic vibrations traverses the same line, the electro-magnet R will tend to obstruct their passage; but another available route is open to them by way of the shunt-circuit, which, in this case, remains unbroken as the rhythmical vibrations are not powerful enough to cause the armature of the electro-magnet [0 be attracted so as to break contact at the stop 3. It is obvious, therefore, that these rhythmical or telephonic vibrations may be transmitted past any required number of stations, and that they will, for the most part, pass around the electromagnets by way of the several shunt-circuits, and that their amplitude will be preserved with little or no diminution.

Fig. 2 shows the application of my invention to a double-acting electro-magnet, having a polarized armature vibrating between fixed contact-stops. In this apparatus, when there is no signaling-current upon the main line, the armaturelever will remain at rest against the front or the rear contact-point inditfcrently, its position depending solely upon the polarity of the current last traversing the line, whether positive or negative. In this case the only modification necessary in applying my invention thereto is to connect the point 4 of the main line to both the front and the rear contact-stops. 3 and 3, as shown in the figure.

It is not at all essential to the operation of my device that the shunt-circuit should be opened and closed by the movement of the armature-lever T, although such an arrangement enables the signaling apparatus to be operated with a considerably less expenditure of electric power.

I sometimes connect the points 2 and 4 by a permanent shunt-circuit, as indicated by the dotted line in Fig. 1, and in such case I insert a double-wound shunt-rheostat, S, therein, as indicated in the drawings.

I do not claim herein the combination of a main circuit with an electro-magnet, and a shunt or branch circuit passing around said electro-magnet, which is automatically closed or broken by interrupting or restoring the current of the main line; neither do I claim the said devices in combination with an artificial resistance inserted in said shunt, as these combinations are claimed in another pending application, of which this is a division.

I claim as my invention The combination, substantially as hereinbefore set forth, of a main circuit, an electromagnet included in said main circuit, a shunt or branch circuit passing around said electromagnet, and a double-wound or other non-inductive artificial resistance included in said shunt-circuit.

In testimony whereof I have hereunto subscribed my name this 15th day of December, A. D. 1880.

FRANCIS \V. JONES.

Witnesses:

WM. ARNOUX, MILLER O. EARL. 

